


Must've done something right

by mistilteinn



Series: Any road you take [2]
Category: Shadowhunters (TV)
Genre: Alec Lightwood has a magic dick, Alec Lightwood wants to marry Magnus Bane, M/M, Magnus Bane Loves Alec Lightwood, Mpreg, Mpreg Magnus, magnus is low-key into feminization, no beta we die like men
Language: English
Status: Completed
Published: 2019-04-10
Updated: 2019-04-10
Packaged: 2020-01-07 14:59:43
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,788
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18413003
Author URL: https://archiveofourown.org/users/mistilteinn/pseuds/mistilteinn
Summary: Catarina covered his hand with her own, smiled at him fondly, and spoke in a kind tone. “Oh, Magnus. You’re four hundred years old. Haven’t you ever heard to be careful what you wish for?”AKA - Magnus gets what he wished for.





	Must've done something right

**Author's Note:**

> here be the second part of a series i never intended to create. i suppose you don't really have to read the first part in order to understand this one, but it might help?
> 
> also, i'm definitely still working through their characterizations! this is my first time writing alec at all, and i'm not sure how i feel about how he turned out
> 
> (title from "Cool" by the jonas brothers)

Magnus frowned as he looked in the mirror, turning this way and that. He had his shirt rucked up under his arms, exposing his flat stomach.

Well, his formerly flat stomach. He frowned harder, a crease appearing between his brows, and poked the skin under his belly button. He turned to look from a different angle and - yes, there was definitely a slight curve there.

He pulled his shirt down and smoothed a hand over the fabric, conflicting feelings racing around his mind. Insecurity, embarrassment, anger at the embarrassment, guilt at the anger, and more.

Magnus sighed, looking over his shoulder at Alec’s sleeping form, and shook his head. Perhaps it was comfort weight from being in a healthy relationship for the first time in the last century. He probably just needed to stop cutting his yoga routines short every morning.

Regardless of his own issues with his changing body, Alexander didn’t seem to have a problem with it. Certainly not if last night’s activities were anything to go by.

A small smile curled his lips and heat twisted deep in his gut as he remembered riding Alexander’s cock, holding him down and taking what he needed, the way that Alexander had begged to touch him.

He looked at his reflection again and sent it a satisfied smirk before turning to leave the bedroom, an extra sway to his hips.

\---

As far as battles alongside the Shadowhunters went, Magnus was pretty happy with this one. He’d been able to trap two Shax demons and keep them away from Izzy while she took on three at once with her whip, as well as banish a Ravener straight back to Edom with a particularly strong spell.

Alexander stood ahead of him and dispatched several other demons with his seraph blade and an arrow in hand. He sliced a Shax down the middle before spinning elegantly and stabbing a charging Hellhound through the chest cavity with his arrow.

He lost his blade when he turned and threw it, impaling a Ravener that had been looming over Magnus’s shoulder. Magnus turned just in time to see it waste away, and created a magical shield to cover their backs.

Ichor sprayed through the air when Alec plucked yet another Shax from its path and tore it into pieces with his rune-enhanced strength, a slightly manic smile on his face. He was - stunning. Watching him fight made Magnus's knees weak.

Magnus’s heart leapt into his throat and he shouted, sending a formless blast of magic at a large demon that appeared out of nowhere, far too close to Alexander for him to get away. His blast hit it straight in the chest and it shattered into innumerable pieces, exploding in a flash of yellow light.

Relief flooded through him, turning his muscles to jelly and making him lightheaded. Suddenly, the sensation grew much stronger and he stumbled to one knee, his magic faltering, the shield around them flickering out.

Darkness fluttered about the edges of his vision and he groaned, clutching his head against a sudden pain. “A - Alexander -” he gasped, the ground flying up towards his face.

\---

When Magnus came to, he was in a bed in the infirmary at the Institute. Alec was holding his hand and watching him intently.

Alec sighed in relief when his eyes fluttered open, his head falling to rest on their joined hands. “Magnus,” he breathed, “I was so worried. Catarina said it’s just exhaustion, but you’ve never fainted in the middle of a battle like that. How do you feel? Is there anything I can get you? Do you need a blanket? Some water? I’m going to get you a blanket and some water.”

He made to stand up, but Magnus held on to his hand, smiled weakly at him, spoke with a scratchy voice. “Please, don’t worry about all that. I’ve got everything I need right here.”

Alec paused, smiled embarrassedly. “Of course. I’m sorry, baby.”

He leaned in and Magnus lifted his face for a kiss, but they were interrupted by a familiar cough coming from the edge of the curtain.

Magnus turned wide eyes to Catarina, who held a clipboard in her hands. She smiled tightly at him and addressed them. “Magnus! Glad to see you’re up! Hey Alec, Magnus looks a little cold. Could you go get him a blanket? Maybe some water?”

Alec nodded hurriedly and straightened up, letting go of Magnus’s hand. He turned back to his boyfriend with serious eyes. “I’ll be right back. I love you.”

“Okay...” Magnus couldn’t help but be disappointed as he watched Alec leave, and he turned, frustrated, to Catarina. “What’s up?”

“Magnus -” Catarina began and stopped herself, casting a silencing spell around the two of them before continuing. “First of all, congratulations. Second of all, what the _hell_ were you thinking?!”

She stepped forward and swatted his arm, sinking into the chair that Alec had previously occupied, resting her head in her free hand. “I cannot believe you’d be so reckless.”

Confusion clouded Magnus’s mind and he yelped at the light smack, rubbing his arm. “What are you talking about? I go out with the Shadowhunters all the time!”

She looked back up at him, eyes flashing dangerously. “Well, you _shouldn’t_ be going out with them in your condition. Absolutely irresponsible - beyond the pale.”

Magnus repeated her words, mind struggling to catch up. “My condition?”

She squinted at him, trying to determine if he was serious. Apparently, she eventually decided that he wasn’t making fun and answered his question. “Yes, your condition, Magnus. You’re pregnant.”

Incredulous, Magnus shot back before he could help it. “Fuck you - _you’re_ pregnant!”

Catarina just raised a rather unimpressed brow at him and he stopped short, immediately embarrassed about shouting at his dearest friend.

“I’m sorry, I’m sorry, I’m sorry. I’m just  - I don’t even have a _womb._ How could I possibly be - ?” Panic and confusion clutching at his throat, Magnus couldn’t bring himself to say it. He just looked down at his stomach under the covers and gestured, looking back up at his friend helplessly.

Catarina shook her head, shrugging her shoulders at a veritable medical miracle in that way that only a seasoned ER nurse could.

Her expression shifted to something softer when she realized that Magnus’s condition was news to him. She spoke in a gentle, no-nonsense tone. “Look - I see weirder things on a weekly basis. Yes, this kind of thing isn’t really _supposed_ to happen for us, but it’s not entirely unheard of. Have you been trying for a baby?”

She paused at his incredulous expression, considering her next words carefully. “Moreso than just not using protection?”

Magnus shifted uncomfortably in the bed, face warming. He averted his eyes, thinking of the past couple of months - how many times Alec had promised to fuck a baby into him, how many times he’d begged for it. How he’d felt the yearning all the way through his soul, how he’d wanted so badly for Alec’s seed to take, to create a new life inside of his body.

“I, um. I guess so.” At her gentle expression, he continued awkwardly. “We’ve been...talking about it on occasion. Just - ah - wishful thinking, really.”

Catarina covered his hand with her own, smiled at him fondly, and spoke in a kind tone. “Oh, Magnus. You’re four hundred years old. Haven’t you ever heard to be careful what you wish for?”

He flushed again and he held her hand tightly, trying to smile through the emotions that rose in his chest. “I suppose - I suppose I thought that saying was just for mortals and fools."

Catarina squeezed his hand and her smile turned mischevious. “I think your assessment still stands - mortals and fools.”

Magnus frowned at her and, after a moment, acquiesced, joining in her laughter.

When they quieted, she patted his hand comfortingly and spoke again. “You have time to figure out what you want to do, and I hope you know that I’ll support you no matter what. But - I think you should talk to Alec about it. He’s part of this too.”

Magnus just nodded at her, mind spinning as he tried to figure out what to tell Alexander.

Catarina pulled him from his thoughts as she continued. “For now, there are some things that we should probably go over. Warlock pregnancy is rare and not very well understood.”

\---

Alec walked into the loft at the end of the day, anxiety prickling at his skin. He knew that Magnus was here, that he was safe and healthy, that Catarina had portalled him directly here once she was done with his check-up at the Institute after pronouncing him extremely exhausted.

He still couldn’t dismiss the idea that something was off, though. Call it his Shadowhunter instincts. Perhaps it was the way that Magnus had collapsed during the fight - the image was burned into Alec’s brain. He’d never seen anything like it, never felt that kind of bone-deep panic before.

“Magnus?” He called out, unable to keep the edge from his voice. Alec sighed in relief when he heard Magnus’s answering shout from the kitchen.

“In here! Dinner’s almost ready!”

Alec dropped his jacket haphazardly in the foyer and toed off his shoes before hurrying into the next room and pulling his boyfriend into a tight embrace, the air around them hot and fragrant with spices.

Magnus yelped at the squeeze and stood on his toes to kiss Alec’s nose. When he went back down, he smiled brightly at Alec and chirped, “Is everything okay? What’s with the anaconda act?”

Alec broke into a smile and pinched his cheek lightly, giddy that Magnus was feeling well enough to poke fun. “I just missed this face, that’s all.” He answered, thinking it likely better not to bring up Magnus’s close call so soon.

Magnus swatted at his hand and wriggled out of his hold, dancing his way back over to the pot on the stovetop and stirring some delightful smelling concoction once he got there. He shot a serious look at Alec when he made to follow and instead pointed at a cabinet, opening it with a blue spark of magic.

“Set the table,” he commanded. “Dinner is almost done.”

Alec blew air out of his mouth and laughed, raising his hands in a placating gesture when Magnus raised his eyebrows impatiently. “Okay, okay, I’ll take care of it.”

A few minutes later, Magnus dished out their dinner and they sat in their usual seats. Alec still felt a strange, anxious buzz under his skin - the sensation made it difficult to eat, regardless of how good Magnus’s cooking smelled.

Magnus looked like he felt it too - he stared intently at Alec instead of his food and almost knocked his glass of water over several times in the span of just a couple of minutes.

Alec took a sip of his beer to calm his nerves and Magnus suddenly broke the silence, blurting out, “I’m pregnant.”

Alec choked on his drink, spitting beer across the table. Eyes wide, he turned to his boyfriend, who stared at him with anxiety etched into his expression. “You’re - I’m _sorry?”_

“I’m pregnant. You know all those times I was like, ‘Fuck a baby into me!’ and you were like, ‘I’m gonna knock you up!’?” Face flushed, Magnus spoke and gestured so quickly that Alec had trouble following, volume increasing with each word until he was very nearly shouting.

“Well, they worked. You did it - you sure did it. Now there’s a baby inside of me and we have to decide if we want it or not and I didn’t even know that this could _happen_ and now it’s _here_ and it’s _happening_ and I’m having your _baby!”_

Eyes wide, Alec placed a hand over Magnus’s, trying to provide comfort as his mind raced to catch up. “Hey, hey, woah, woah. Hey, it’s okay. Start from the beginning - how did this happen? I thought that wasn’t possible?”

Magnus looked exhausted and miserable; he dropped his head for a moment. When he brought it back up, he met Alec’s gaze hesitantly. His voice was much softer than before, no longer carried the edge of hysteria. “I thought so too, until today. Catarina and I talked about it in the infirmary. Apparently,” he paused and sighed, swallowing before he continued. “Apparently, there’s something about your angel blood and my demon blood and the level of magic present in both of us together that made it possible. I didn’t know, I swear.”

Alec was silent for a few moments, gears turning in his mind. Magnus looked beseechingly at him, desperate for a response of some kind.

“So you’re saying…” Alec began, brow furrowed. Magnus leaned forward, holding his hand.

“That it _was_ my Shadowhunter abilities,” he declared, a beatific smile on his face.

Magnus’s jaw dropped and he tilted his head, dumbfounded.

Alec continued, excitement growing. _“And_ my magic dick!”

After an extended pause, Magnus shook his head slowly. “That’s not at all - please,  _please_ never refer to your dick as magic again.”

Alec just smiled brilliantly at him, speaking once more as he processed the news. “We’re having a baby…. _you_ and _I_ are going to have a _baby?”_

Soul-deep euphoria rose in his chest at Magnus’s small nod, and he wasn’t entirely surprised when his phone chimed on the table. He glanced at it before tucking it away into his pocket.

Sure enough, there was a message from Jace, congratulating him on finally working up the nerve to propose. He could correct his brother later.

He turned his full attention back to Magnus, no more able to wipe the goofy smile off his face than he would be able to banish the elation from his heart. “Mangus, this is incredible.”

For the first time since dinner began, his boyfriend let go of some of the tension in his body. His shoulders slumped a little and his eyes fell shut. He blew out a long breath from his mouth and when his eyes fluttered open again, he addressed Alexander. “You’re not - you’re not mad at me?”

It was Alec’s turn to be dumbfounded. “Why in the world would I be mad at you? This is what I wished for - what I wanted more than anything. Ever since you first said something about it, it’s all I’ve been able to dream about.”

A horrible thought occurred to him, and he continued, careful to keep his voice steady. “Is it… Is it not what you wanted?”

Magnus shook his head quickly, clutching Alec’s hand in his own. The strong grip loosened the sudden tightness in his chest, and he breathed deeply as Magnus spoke, voice raw. “Of course it’s what I want. I just - I didn’t want you to think that I intentionally tricked you into it.”

Alec considered the man sitting in front of him for a few moments. Brilliant - of course. Beautiful - beyond compare. Mischevious - sometimes, certainly. Deceptive - on occasion, if a mission necessitated it. But not about this - never about something as serious as a child.

He shook his head, more certain than ever, his thumb rubbing over Magnus’s hand. “I’d never think that. I know your soul, Magnus, and I know that it’s not in you to intentionally keep something like that from me.”

The last bit of tension leaked out of Magnus at that, and he dropped his head against their joined hands, let out a deep, relieved sigh.

Alec stood, pulled him out of his seat and into a hug. He clutched Magnus’s back with his free hand, rested his head atop the warlock’s. Magnus shuddered in his arms, relaxed in his hold. “It’s okay,” Alec spoke softly, a never-before-felt sense of contentment swirling in his chest. “I’m right here. I love you, I love our baby, I love that we’re gonna get to do this together.”

Magnus fisted a hand in his shirt and mumbled into his chest wetly. “I was so worried. I don’t even understand why I was so worried? Of course you wanted this too. It couldn’t have happened if you didn’t.”

Alec pushed back a smile, breathed in the scent of sandalwood in Magnus’s hair and patted his back as he sniffled. “It’s okay, sweetheart. It’s okay.”

\---

In bed later, Alec curled an arm around Magnus’s back, tucked his head under his chin. Magnus hummed sleepily at the treatment, pressing his face closer and snuffling against Alec’s neck.

Alec couldn’t help the smile that bloomed over his face, drowsily vowing to remember this moment the next time Magnus accused him of snoring.

He brushed his hand over Magnus’s shoulder blade, smoothing the muscles bunched under his soft skin. Magnus seemed to melt under his touch, letting out a sound close to a purr before he shifted his legs and woke up, tensing abruptly.

“Magnus?” Alec murmured, voice low and soft. “Are you okay?”

His boyfriend pulled out of his hold and sat up in their bed for a second, the light from the streets outside reflecting eerily on his gold eyes. He let out a distressed noise and stood quickly, stumbling his way into the master bathroom.

Unease rolling through his veins, Alec stood quickly and followed him, flicking on the light when he crossed the threshold. Magnus groaned at him from his place in front of the toilet before he leaned over it and vomited.

“Magnus - are you sick? Was it something you ate?” Alec asked as he filled a cup with water and rushed to Magnus’s side. He braced his head with one hand, felt his forehead with the back of the other, then let out a relieved breath when his temperature felt normal.

Magnus just shook his head, looking miserable, before he leaned over the toilet and heaved again.

Alec connected the dots and exclaimed a soft  _oh_  before rubbing Magnus’s back soothingly. “It’s okay, just let it out,” he cooed, wondering wildly how he could possibly help Magnus feel better. His mother! She’d been pregnant before - she would know how to help.

“Hold on, baby, I’m gonna call my mom - she’ll know what to do.”

Magnus grabbed his arm with an iron grip and turned from the toilet bowl, eyes teary and frown intense. “Are you _insane,”_ he hissed.

“It’s -” he turned Alec’s hand over in his own to check his watch, “- two thirty in the morning. We are _not_ calling your mother and giving her the news that she’s going to be a grandmother until a decent hour - five o’clock at the _very_ earliest!”

“Right, you’re right,” Alec bit back a fond smile, charmed as ever by his boyfriend. “Five o’clock at the very earliest.”

Magnus sniffed and nodded before turning to throw up again, his entire body trembling with the heaves. Alec grimaced and ran his fingers through the hair at the nape of Magnus’s neck, making encouraging noises and rubbing his back.

When Magnus was done, he leaned back heavily into Alec’s waiting arms, taking the proffered cup of water and rinsing his mouth.

Alec pressed a kiss to the top of his head and let a smile curl across his face at the thought of telling their loved ones. He wondered how long Magnus would want to wait. He wondered if Magnus would want to find out the sex of the baby. He hoped it was a girl. Or a boy. Or both - or neither! - as long as it was healthy.

He was pulled from his thoughts when Magnus shuddered in his arms. “Hey, what’s wrong?” Alec asked, immediately concerned.

Magnus leaned back against him and spoke, sounding miserable. “I - I just realized. Our baby’s going to be a bastard.”

Alec’s grip tightened and his heart thumped as he thought of the ring he had stashed in his bedside table. “Sweetheart,” he began, shifting them both so that Magnus was facing him, their legs tangled together on the bathroom floor. He nodded as he spoke, eyes wide and sincere. “I’ll marry you right now. You want to get married? We can do that today.”

“Alexander,” Magnus frowned heavily at him, looking for all the world as if Alec had gravely offended him. “I don’t want a _shotgun wedding -_ I need at least a year to find a venue, let alone come up with a halfway reasonable guest list. Have you any idea how many Downworlders to whom I’ve promised front row seats in exchange for favors over the years? How many people will expect to be in the wedding party? Lily Chen will actually start a war if she finds out I got married and didn’t name her one of my bridesmaids.”

Magnus paused and tilted his head, brow furrowed. “Groomsmaids?”

“Groomsmaids, I think.” Alec easily agreed, fingers absently running up and down Magnus’s arm, and decided to tease him a bit. “Unless - you _want_ to be my bride? Have Raphael walk you down the aisle? Wear a white dress for me in front of all of our guests?”

Magnus flushed at that, looked down between them. “Perhaps,” he hedged, and Alec quirked a smile at him, cradled his face in one of his hands.

“Whenever you want to get married, whatever you want to wear, whoever you want to invite, I will be there.” Alec spoke seriously, wanting - no, needing Magnus to understand. “You’ve already given me everything I could ever ask for. Our wedding day is going to be all about you.”

Magnus nuzzled into his hand and blinked, sending him a watery smile. He leaned in close and his eyes flickered between his glamour and their natural gold. Alec’s breath caught in his throat at the sight, and he leaned in as well so that they were sharing air.

“Alexander,” Magnus began, speaking softly and tangling both of their hands together. “Can you imagine it? Our wedding is going to be the best party that has ever happened. Ever.” He leaned in even closer, their noses brushing together, emphasizing each word as he whispered. “It is going to blow Truman Capote’s Black and White Ball out of the water.”

Alec laughed, delighted and surprised by the the determined spark in Magnus’s eyes. Love bloomed in his chest, and he gathered his boyfriend - fiancé? - in his arms, pulling him up so that they could go back to their room.

“C’mon, let’s go to bed. I’m gonna put another baby in you,” he teased, his smile growing when Magnus faltered in the doorway and looked up at him, eyes wide and golden.

“Yeah - yeah, that sounds good. Great, even. Definitely do that,” Magnus stumbled over his words and stepped ahead of him, tugging on his hand. “Right now, come on.”

 

**Author's Note:**

> HUGE S/O to my lovely friend Cait (sorryallonsy here on AO3) for the line "Gonna put another baby in you" <3 <3 <3
> 
> definitely leave a comment or kudos if you have any thoughts or opinions about this - i am WAY out of my depth here!
> 
> and please let me know if you want more of this? i low-key really want to write some kinky pregnancy sex (hello "gonna put another baby in you"), but i have no clue if anyone is even interested?
> 
> (also, yes, i paralleled several scenes and pieces of dialogue from the first part and from the show - i love doing that kind of thing)


End file.
